Source: lib/media/transmuxer.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.media.Transmuxer');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.util.BufferUtils');
  11. goog.require('shaka.util.Error');
  12. goog.require('shaka.util.IDestroyable');
  13. goog.require('shaka.util.ManifestParserUtils');
  14. goog.require('shaka.util.PublicPromise');
  15. goog.require('shaka.util.Uint8ArrayUtils');
  16. goog.require('shaka.dependencies');
  19. /**
  20.  * Transmuxer provides all operations for transmuxing from Transport
  21.  * Stream to MP4.
  22.  *
  23.  * @implements {shaka.util.IDestroyable}
  24.  */
  25. shaka.media.Transmuxer = class {
  26.   /** */
  27.   constructor() {
  28.     /** @private {?muxjs} */
  29.     this.muxjs_ = shaka.dependencies.muxjs();
  31.     /** @private {muxjs.mp4.Transmuxer} */
  32.     this.muxTransmuxer_ = new this.muxjs_.mp4.Transmuxer({
  33.       'keepOriginalTimestamps': true,
  34.     });
  36.     /** @private {shaka.util.PublicPromise} */
  37.     this.transmuxPromise_ = null;
  39.     /** @private {!Array.<!Uint8Array>} */
  40.     this.transmuxedData_ = [];
  42.     /** @private {!Array.<muxjs.mp4.ClosedCaption>} */
  43.     this.captions_ = [];
  45.     /** @private {!Array.<muxjs.mp4.Metadata>} */
  46.     this.metadata_ = [];
  48.     /** @private {boolean} */
  49.     this.isTransmuxing_ = false;
  51.     this.muxTransmuxer_.on('data', (segment) => this.onTransmuxed_(segment));
  53.     this.muxTransmuxer_.on('done', () => this.onTransmuxDone_());
  54.   }
  56.   /**
  57.    * @override
  58.    */
  59.   destroy() {
  60.     this.muxTransmuxer_.dispose();
  61.     this.muxTransmuxer_ = null;
  62.     return Promise.resolve();
  63.   }
  66.   /**
  67.    * Check if the content type is Transport Stream, and if muxjs is loaded.
  68.    * @param {string} mimeType
  69.    * @param {string=} contentType
  70.    * @return {boolean}
  71.    */
  72.   static isSupported(mimeType, contentType) {
  73.     const Transmuxer = shaka.media.Transmuxer;
  75.     if (!shaka.dependencies.muxjs() || !Transmuxer.isTsContainer(mimeType)) {
  76.       return false;
  77.     }
  79.     if (contentType) {
  80.       return MediaSource.isTypeSupported(
  81.           Transmuxer.convertTsCodecs(contentType, mimeType));
  82.     }
  84.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  86.     const audioMime = Transmuxer.convertTsCodecs(ContentType.AUDIO, mimeType);
  87.     const videoMime = Transmuxer.convertTsCodecs(ContentType.VIDEO, mimeType);
  88.     return MediaSource.isTypeSupported(audioMime) ||
  89.         MediaSource.isTypeSupported(videoMime);
  90.   }
  93.   /**
  94.    * Check if the mimetype contains 'mp2t'.
  95.    * @param {string} mimeType
  96.    * @return {boolean}
  97.    */
  98.   static isTsContainer(mimeType) {
  99.     return mimeType.toLowerCase().split(';')[0].split('/')[1] == 'mp2t';
  100.   }
  103.   /**
  104.    * For transport stream, convert its codecs to MP4 codecs.
  105.    * @param {string} contentType
  106.    * @param {string} tsMimeType
  107.    * @return {string}
  108.    */
  109.   static convertTsCodecs(contentType, tsMimeType) {
  110.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  111.     let mp4MimeType = tsMimeType.replace(/mp2t/i, 'mp4');
  112.     if (contentType == ContentType.AUDIO) {
  113.       mp4MimeType = mp4MimeType.replace('video', 'audio');
  114.     }
  116.     // Handle legacy AVC1 codec strings (pre-RFC 6381).
  117.     // Look for "avc1.<profile>.<level>", where profile is:
  118.     //   66 (baseline => 0x42)
  119.     //   77 (main => 0x4d)
  120.     //   100 (high => 0x64)
  121.     // Reference: https://bit.ly/2K9JI3x
  122.     const match = /avc1\.(66|77|100)\.(\d+)/.exec(mp4MimeType);
  123.     if (match) {
  124.       let newCodecString = 'avc1.';
  126.       const profile = match[1];
  127.       if (profile == '66') {
  128.         newCodecString += '4200';
  129.       } else if (profile == '77') {
  130.         newCodecString += '4d00';
  131.       } else {
  132.         goog.asserts.assert(profile == '100',
  133.             'Legacy avc1 parsing code out of sync with regex!');
  134.         newCodecString += '6400';
  135.       }
  137.       // Convert the level to hex and append to the codec string.
  138.       const level = Number(match[2]);
  139.       goog.asserts.assert(level < 256,
  140.           'Invalid legacy avc1 level number!');
  141.       newCodecString += (level >> 4).toString(16);
  142.       newCodecString += (level & 0xf).toString(16);
  144.       mp4MimeType = mp4MimeType.replace(match[0], newCodecString);
  145.     }
  147.     return mp4MimeType;
  148.   }
  151.   /**
  152.    * Transmux from Transport stream to MP4, using the mux.js library.
  153.    * @param {BufferSource} data
  154.    * @return {!Promise.<{data: !Uint8Array,
  155.    *                     captions: !Array.<!muxjs.mp4.ClosedCaption>,
  156.    *                     metadata: !Array.<!Object>}>}
  157.    */
  158.   transmux(data) {
  159.     goog.asserts.assert(!this.isTransmuxing_,
  160.         'No transmuxing should be in progress.');
  161.     this.isTransmuxing_ = true;
  162.     this.transmuxPromise_ = new shaka.util.PublicPromise();
  163.     this.transmuxedData_ = [];
  164.     this.captions_ = [];
  165.     this.metadata_ = [];
  167.     const dataArray = shaka.util.BufferUtils.toUint8(data);
  168.     this.muxTransmuxer_.push(dataArray);
  169.     this.muxTransmuxer_.flush();
  171.     // Workaround for https://bit.ly/Shaka1449 mux.js not
  172.     // emitting 'data' and 'done' events.
  173.     // mux.js code is synchronous, so if onTransmuxDone_ has
  174.     // not been called by now, it's not going to be.
  175.     // Treat it as a transmuxing failure and reject the promise.
  176.     if (this.isTransmuxing_) {
  177.       this.transmuxPromise_.reject(new shaka.util.Error(
  178.           shaka.util.Error.Severity.CRITICAL,
  179.           shaka.util.Error.Category.MEDIA,
  180.           shaka.util.Error.Code.TRANSMUXING_FAILED));
  181.     }
  182.     return this.transmuxPromise_;
  183.   }
  186.   /**
  187.    * Handles the 'data' event of the transmuxer.
  188.    * Extracts the cues from the transmuxed segment, and adds them to an array.
  189.    * Stores the transmuxed data in another array, to pass it back to
  190.    * MediaSourceEngine, and append to the source buffer.
  191.    *
  192.    * @param {muxjs.mp4.Transmuxer.Segment} segment
  193.    * @private
  194.    */
  195.   onTransmuxed_(segment) {
  196.     this.captions_ = segment.captions;
  197.     this.metadata_ = segment.metadata;
  198.     this.transmuxedData_.push(
  199.         shaka.util.Uint8ArrayUtils.concat(segment.initSegment, segment.data));
  200.   }
  203.   /**
  204.    * Handles the 'done' event of the transmuxer.
  205.    * Resolves the transmux Promise, and returns the transmuxed data.
  206.    * @private
  207.    */
  208.   onTransmuxDone_() {
  209.     const output = {
  210.       data: shaka.util.Uint8ArrayUtils.concat(...this.transmuxedData_),
  211.       captions: this.captions_,
  212.       metadata: this.metadata_,
  213.     };
  215.     this.transmuxPromise_.resolve(output);
  216.     this.isTransmuxing_ = false;
  217.   }
  218. };